There are a number of different modes of music, each of which comprises a series of diatonic scales. Each diatonic scale comprises a series of seven steps, rising from one tone to its octave. The steps between the degrees (notes) of a scale are either a semitone or a tone in magnitude. Each of the different modes of music has its own characteristic sequence of tone and semitone steps or intervals between successive degrees of its scales. All of the diatonic scales of a given mode of music have the tone-semitone sequence characteristic of that mode.
The most familiar modes of music in Western culture are the major scale (also known as the Ionian Mode), and the Aeolian or minor mode (from which Western minor scales are derived). The major mode has the following sequence of steps: EQU tone-tone-semitone-tone-tone-tone-semitone
Thus in a major scale which starts and finishes on the note C (i.e. in which C is the tonic or keynote), known as the scale (key) of C major, the degrees which must comprise the scale are dictated by the above interval sequence, and are as follows:
______________________________________ tone tone semitone tone tone tone semitone C- D- E- F- G- A- B- C- tonic tonic ______________________________________
If D is chosen as the tonic note, the resulting scale of D major uses F sharp as the third note or degree instead of F natural and C sharp as the seventh note or degree instead of C natural, thereby maintaining the characteristic tone-semitone interval sequence of the major mode.
Other modes of music have different sequences of tone-semitone intervals between adjacent degrees of their diatonic scales. A thorough familiarity with the sequences characteristic of various modes of music facilitates playing by ear.
In the past, musical compositions in the Western culture have generally been written and played in accordance with one mode of music, at least for long passages of the composition. Any change from one mode, e.g. major, to another mode, e.g. Aeolian has normally represented a distinct transition point in the music, between separate passages thereof, except for occasional use of chords from another mode. It is seldom that more than two different modes of music are incorporated into the same composition.
There is currently, however, more and more attention being paid by composers and musicians alike to other modes of music, in addition to the familiar major and Aeolian minor modes, in particular the Phrygian mode, the Mixolydian mode and the Dorian mode. Numerous other modes of music are known, but the other modes do not fit the accepted harmonic patterns of music found in the Western culture. Up until fairly recently, the aforementioned modes have been regarded as archaic musical forms, and have not had a significant role in Western Culture. However, as composers and musicians continually strive for new and varied effects in their music, these previously disregarded modes are being used to a greater extent. There is also a tendency, in modern music, to "mix" the various modes of music in a single composition, and to make frequent and abrupt changes from one mode to another in the composition. One way of achieving this is to introduce into a musical passage written in a given mode, one or more chords which are derived from another mode. These chords thereby provide transition points for changing from one mode of music to another.
Accordingly, for the student of music, as well as for the composer, there is an increasing need to study and understand at least the five different modes of music referred to above, namely major (Ionian), Aeolian, Mixolydian, Dorian and Phrygian, and their relationship with one another. It is also helpful to know the various chords and characteristics thereof which can be used in different modes of music.